Electromagnetically releasable latching means with floating latch member

ABSTRACT

An electromagnetically releasable floating latch mechanism holds an electromagnetic contactor device in energized position by engaging and latching the armature when it reaches attracted position after energization of the contactor. The floating latch member is pivotable about a fulcrum that is slidable laterally. A spring presses against an arm on, and extending perpendicular to, the latch member to bias the latch toward latching position. A solenoid magnet, when energized, attracts the latch to release it.

United States Patent Inventor Harold E. Schleicher West Hartlord, Conn. 37,206

May 14,1970

Jan. 1 l, 1972 Arrow-Hart, Inc.

Appl. No. Filed Patented Assignee ELECTROMAGNETICALLY RELEASABLE LATCHING MEANS WITH FLOATING LATCH MEMBER 11 Claims, 4 Drawing Figs.

US. Cl 335/170 Int. Cl t l-l0lh 9/20 Field of Search 335/170,

References Cited UNITED STATES PATENTS 3,312,808 4/1967 Dehn 335/170 2,148,295 2/1939 Hays 337/53 3,076,074 1/1963 Landow et al. 335/174 Primary Examiner-Harold Broome AttorneyDavis, Hoxie, Faithfull & Hapgood energized, attracts the latch to release it.

a Z a a a ll ELECTROMAGNETICALLY RELEASABLE LATCHING MEANS WITH FLOATING LATCH MEMBER PRIOR ART It is common to close electromagnetic contactors by momentary energization of an electric solenoid coil, a holding coil circuit thereupon being energized to maintain the contactor closed. In contrast to magnetically held contactors, there are mechanically held contactors. These have a mechanical latching means to hold the' contactor closed instead of the holding coil and its circuit. I

Mechanically held contactors are desired where inherent AC hum of permanently energized magnetic holding coils is objectionable and where loss of voltage for an instant or short for a long period and momentary to occur; 7

Although mechanical holding means for electromagnetic contactors have been known, they have often involved complex mechanisms of links, levers, and latches, which require careful fabrication and relatively costly assembly.

SUMMARY OF THE INVENTION According to the present invention, a latching unit is provided which can be attached to conventional electromagnetic switches, in the field, without the use of special hardware or screws. The unit comprises an insulated housing within which is mounted a latch member having a nose extending outside of the casing in position to engage an extending part of the contact carrier of a conventional electromagnetic contactor. The

latch is floatingly mounted in the casing by trunnions which slide in slots in the casing, while a biasing spring acts on the latch in a direction to cause the latch to normally lie in the path of movement of the extending part of the contact carrier of the electromagnetic contactor. The biasing spring exercises period would allow-the contactor to drop out with accom- I panying loss of service. Mechanically latched contactors are also desired where it is desired to maintain a contactor closed power interruption is likely a rotary force tending to pivot the latch about its trunnions and at the same time exercises a force longitudinally of the latch, Whose top engages an angular surface on the casing to exercise a component of force in the same direction as the rotary force. The latch is released by an electromagnetic releasing means consisting of an armature mounted on the latch and acted upon by a conventional electric solenoid coil and field piece when the solenoid is energized.

DESCRIPTION OF THE INVENTION It is an object of this invention to provide an improved mechanical latch unit for an electromagnetic contactor without links or levers and which is easy to make and assemble.

Another object is to provide a unit as aforesaid which has one main latching element with biasing means therefore, and which can be released electromagnetically.

Still another object is to provide a mechanical latch device as aforesaid which can be attached to an existing electromagnetic contactor in the field without additional hardware or screws.

Still another object is to provide a latch device as aforesaid in which the latch is floatingly mounted and pivotable about a floating fulcrum.

Other objects and advantages of the invention will appear as it is described in connection with the accompanying drawings.

In the drawings,

FIG. 1 is a side elevational view of an electromagnetic contactor to which the latchunit of the invention may be attached without extra hardware or screws.

FIG. 2, is a side elevational view of the latch unit embodying the invention.

FIG. 3 is an elevational sectional view along line 3-3 of FIG. 2.

FIG. 4 is an elevational sectional view along line 4-4 of FIG. 3, with the cover removed.

Referring to the drawings, FIG. 1 illustrates an electromagnetic contactor as fully described and claimed in my copend-- ing application, Ser. No. 704,363, issued on Dec. 29, I970, as

US. Pat. No. 3,551,859, to which reference may be made for a detailed explanation of its structure. The contactor has an",

armature. assembly comprising a pair of spaced bellcrank levers, each having arms 31 and 39, pivotally mounted by trunnions 32 seating in notches 16 in a base 10. Arms 31 of the bellcrank levers have bifurcated ends engaging lateral extensions 28 of a reciprocating contact carrier (not visible) for the J movable contacts. The contact carrier is biased by a pair of coiled compression springs, such as 29, to oppose the move- The latching device is housed in the casing 50 of molded insulating material having separate cover part 51 secured upon a deep hollow base part 52 within which are contained the operating parts of the device. The casing may be rectangular or any other suitable or conventional shape. Formed in that wall 52] of the base which faces and abuts the contactor is a 1 slot or recess 53 through which extends nose 61 of a floating latch member designated generally by the numeral 60. The latch member is generally cross-shaped, having a vertical or lever part 63 extending from the floor of the base toward the cover 51, and two arms, 64', 64", extending laterally from the lever part 63 toward the sidewalls of the base. For pivotally mounting the latch 60, trunnions 65', 65", extend laterally from the lever part 63 of the latch near its lower or inner end in position to slide in cooperating aligned slots 55', 55", formed in the bottom part of the base 52 parallel to the wall 52f.

In order to bias the latch toward latching position, one end (the bottom end) of a. coiled compression spring 68 is seated on a nub 57 in the floor of the casing. The line of action of the spring is offset from the lever part 63 in position to engage an arm 66 which extends laterally from the lower midportion of the lever part 63. A nub 67 on the arm 66 anchors the upper end of the spring 68 which presses at its upper end against the arm 66, tending to urge the latch counterclockwise (referring to FIG. 3). However, due to the trunnion pivots 65', 65",

being slidingly mounted in the slots 55 in the base, the lever 63 is not only urged counterclockwise by the spring 68, but is also biased upwardly toward the cover 51. The inner surface 51a of I the cover 61 is formed with a slight upward and outward angular inclination, so that when the curved upper or top surface of nose 61 engages the inclined surface 51a, a component of the upward force of the spring 68 acts on the latch, tending to move it outwardly, i.e., to the left, in FIG. 3, assisting the outward biased force of the spring against the lateral arm 66.

Thus, when the electromagnet is deenergized, the end of the lateral extension 28 of the contactors contact carrier is in the upper (dotted) position of FIG. 2, but on energization of the electromagnet, the lateral extension 28 moves down and engages the upper inclined surface of the nose and forces it down and to the right (referring to FIG. 3), until the lateral extension 28 moves past the nose, whereupon the latch snaps to the left over the contact-carrier extension 28, holding the contact carrier of the contactor in engaged or closed position.

In order to cause disengagement of the latch nose 61 from the lateral extension 28, an electromagnetically operated releasing means is provided, comprising a conventional laminated, flat armature 70 of magnetic material, mounted on the latch 60 in recesses formed in its side of the arms 64', 64' facing away from the wall 52f of the base. Adjacent the armature 70 is a conventional laminated, E-shaped fieldpiece 80 of magnetic material around the center arm of which is a solenoid coil 82, which when energized by the electric current, causes the armature to be attracted toward the fieldpiece. This pulls the latch inwardly and disengages the nose 61 from the lateral extension 28 of the movable contact carrier. This allows the biasing spring 29 of the contactor to cause the contactor to drop out.

Suitable pigtail leads 84', 84", from the solenoid coil 82, may be led out of the casing 50 and connected to terminals mounted on casing 50 on top of the cover. The terminals may be secured to the cover by screws which pass through it into the base 50 so that the cover is held to the base by the same screws that hold the terminals to the cover.

For the purpose of enabling attachment of the latch unit to the contactor, the outer face of wall 52f has a pair of spaced parallel slots 54a, 54b, molded into it to-receive the ribs 14a, 14b, on the contactor base 10. The slots have their side edges bevelled to accommodate the dovetail form of the ribs. When attached to the contactor, the unit is held against removal by the edge of the insulating block 40 of the contactor which edge slightly overhangs the adjacent edge of the latch unit.

From the foregoing, it will be observed that the invention provides a single latch member floatingly mounted in a base in position to engage the contact carrier of the electromagnetic contactor by the normal biasing action of a single spring, which not only urges the latch to pivot about its trunnions, but also urges the latch toward engaging position by the action of a component of the spring exercised through the engagement of the latch nose against an inclined surface on the cover of the casing.

Many modifications within the scope of the invention will occur to those skilled in the art. Therefore, the invention is not limited to the specific form illustrated and described.

What is claimed is:

l. A latch and latch release unit for use with an electromagnetic contactor of the type which includes an insulating base means, fixed contact means and movable contact means engageable therewith, supported from said base means, and electromagnetic operating means for operating said movable contact means, said unit comprising an insulating casing, latching means, pivot means for said latching means for pivotally supporting said latching means from said casing, bearing means in which said pivot means is slidable laterally with respect to the pivotal axis to permit said latching means to move longitudinally as well as pivotally, and means biasing said latching means toward a position for latching engagement with the operating means of said contactor when said contact means are engaged.

2. A unit as claimed in claim 1 having means on said casing engageable by said latching means to cause a component of force of said biasing means exerted longitudinally of the latching means to be directed in a latching direction.

3. A unit as claimed in claim 2 in which the componentdirecting means includes a camming surface on the casing engaged by the latching means.

4. A unit as claimed in claim 3 in which the biasing means includes a coiled compression spring engaging said latching means at a point offset laterally from the pivotal axis of said pivot means.

5. A unit as claimed in claim 1 in which the biasing means includes a coiled compression spring engaging said latching means at a point offset laterally from the pivotal axis of said pivot means.

6. A unit as claimed in claim 2 in which the biasing means includes a coiled compression spring engaging said latching means at a point offset laterally from the pivotal axis of said pivot means.

7. A unit as claimed in claim 1 in which said pivot means includes trunnion pivots on said latching means slidable in a slot in said casing to permit said longitudinal as well as said pivotal movement of the latching member.

8. A unit as claimed in claim 1 in which said pivot means includes a pivot and slot connection between said latching means and easing.

9. A unit as claimed in claim 1 having an armature mounted on said latching means and electromagnetic solenoid coil means with said casing energizable to withdraw said latching means from latching position.

10. A unit as claimed in claim 1 in which the casing comprises a base part and a cover part secured to said base part, said pivot means being within said base part and said cover part holding said latching means in sliding engagement within said bearing means.

11. A unit as claimed in claim 2 in which the casing comprises a base part and a cover part secured to the base part, and said component-directing means comprises a camming surface on said cover part engaged by said latching means. 

1. A latch and latch release unit for use with an electromagnetic contactor of the type which includes an insulating base means, fixed contact means and movable contact means engageable therewith, supported from said base means, and electromagnetic operating means for operating said movable contact means, said unit comprising an insulating casing, latching means, pivot means for said latching means for pivotally supporting said latching means from said casing, bearing means in which said pivot means is slidable laterally with respect to the pivotal axis to permit said latching means to move longitudinally as well as pivotally, and means biasing said latching means toward a position for latching engagement with the oPerating means of said contactor when said contact means are engaged.
 2. A unit as claimed in claim 1 having means on said casing engageable by said latching means to cause a component of force of said biasing means exerted longitudinally of the latching means to be directed in a latching direction.
 3. A unit as claimed in claim 2 in which the component-directing means includes a camming surface on the casing engaged by the latching means.
 4. A unit as claimed in claim 3 in which the biasing means includes a coiled compression spring engaging said latching means at a point offset laterally from the pivotal axis of said pivot means.
 5. A unit as claimed in claim 1 in which the biasing means includes a coiled compression spring engaging said latching means at a point offset laterally from the pivotal axis of said pivot means.
 6. A unit as claimed in claim 2 in which the biasing means includes a coiled compression spring engaging said latching means at a point offset laterally from the pivotal axis of said pivot means.
 7. A unit as claimed in claim 1 in which said pivot means includes trunnion pivots on said latching means slidable in a slot in said casing to permit said longitudinal as well as said pivotal movement of the latching member.
 8. A unit as claimed in claim 1 in which said pivot means includes a pivot and slot connection between said latching means and casing.
 9. A unit as claimed in claim 1 having an armature mounted on said latching means and electromagnetic solenoid coil means with said casing energizable to withdraw said latching means from latching position.
 10. A unit as claimed in claim 1 in which the casing comprises a base part and a cover part secured to said base part, said pivot means being within said base part and said cover part holding said latching means in sliding engagement within said bearing means.
 11. A unit as claimed in claim 2 in which the casing comprises a base part and a cover part secured to the base part, and said component-directing means comprises a camming surface on said cover part engaged by said latching means. 